The semiconductor optoelectronic devices contribute to data transmission and energy conversion along with the advance of technology. For example, the semiconductor optoelectronics devices can be applied in systems such as the optical fiber communication, optical storage, military system, and the like. In general, the processes of forming semiconductor optoelectronic devices include forming wafers, growing epitaxy layers, growing thin films, diffusion/ion implantation, photolithography, etching, and the like.
In the described processes, growing epitaxy layers are generally performed by a chemical vapor deposition (CVD) system or a molecular beam epitaxy (MBE) system. The CVD system is preferred in this industry because of its faster production rate compared with the MBE system.
FIG. 1 shows a cross-sectional diagram of major parts of a conventional epitaxial growth system-chemical vapor deposition system 1 for semiconductor optoelectronic devices. In system 1, a base plate 101 is combined with an enclosure 102 to form a sealed reactor chamber 103. A susceptor 104 is contained in the reactor chamber 103. The susceptor 104 has a horizontal supporting surface 105 with a plurality of wafer fixing elements (not shown) thereon. The wafer fixing elements fix a plurality of wafers 106 on the supporting surface 105, and the fixed wafers 106 can be subsequently processed by epitaxial growth. In addition, several inductive coils 107 are disposed under the supporting surface 105 to heat the wafers thereon. The inductive coils 107 are supplied with electricity, and thereby form an electromagnetic induction to heat the wafer 106 on the susceptor 104. In this system, the inductive coils 107 are arranged in curve relative to the supporting surface 105. Therefore, the wafers 106 can be uniformly heated by the inductive coils 107. In other words, a rotation device 108 is set as a reference to separate the inductive coils 107 to left and right parts. The remote portion of the inductive coils 107 (far away from the reference) are apart from the supporting surface 105 with a shorter distance, and the center portion of the inductive coils 107 (near the reference) are apart from the supporting surface 105 with a larger distance. In addition, the rotation device 108 is connected to the center of the susceptor 104 such that the susceptor 104 can be rotated. Therefore, the wafers 106 fixed on different locations of the susceptor 104 can be heated with higher uniformity. The internal part of the rotation device 108 can be further connected to a gas line 109, thereby connecting to an external gas supply system. The gas line is used to input a gas to the reactor chamber for the epitaxial growth. Simultaneously, the susceptor 104 is rotated by the rotation device 108, and uniformly heated by the lower heating system. Afterwards, an epitaxy layer is formed on the surface of the wafers 106.
In the conventional epitaxial growth system 1 for semiconductor optoelectronic devices, the upper wafers 106 are heated by electromagnetic induction of the inductive coils 107. The inductive coils 107 are arranged in curve related to the supporting surface 105. The curved degree of the arrangement is defined by the distance between the inductive coils 107 and the upper wafers 106, and the density of the arrangement is defined by the distance of the inductive coils therebetween. The temperature uniformity depends on the curved degree and the density of the arrangement so the temperature tuning is quite complicated. When the device material and/or the epitaxy reaction temperature are changed, the whole arrangement of the inductive coils 107 has to be correspondingly tuned. Moreover, if the temperature uniformity of the wafers 106 is tuned by increasing/decreasing the applied electromagnetic energy, the temperature is dramatically interfered with the circumstance temperature. In short, it is difficult to control the heating uniformity of the wafers 106.